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Efficient, User-Driven Data Acknowledgement between Two Communication Entities

IP.com Disclosure Number: IPCOM000111936D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 6 page(s) / 152K

Publishing Venue

IBM

Related People

Horton, VG: AUTHOR [+8]

Abstract

In many computer configurations that support data communications, the data link layer communications support is implemented within a subsystem. To utilize the communications support, the host system exchanges information in the form of primitive constructs within the subsystem. The data acknowledgement process may consist of several exchanges between the requester and the provider of the data transmission service.

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Efficient, User-Driven Data Acknowledgement between Two Communication
Entities

      In many computer configurations that support data
communications, the data link layer communications support is
implemented within a subsystem.  To utilize the communications
support, the host system exchanges information in the form of
primitive constructs within the subsystem.  The data acknowledgement
process may consist of several exchanges between the requester and
the provider of the data transmission service.

      Data is transferred and acknowledged between two peer entities
by means of a protocol.  Outgoing data is first passed from a sending
(user) entity to its provider of the data transmission service using
constructs, called primitives.  The user maintains an active copy of
this data until it receives an acknowledgement that the data has been
correctly received by the remote destination.  The receiving
(provider) entity is responsible for receiving the acknowledgement
and sending a primitive construct to the user when the remote
response has been obtained.  Fig. 1 is an example of a
system-to-system data acknowledgement scenario.

      In Fig. 1, the user entity, for those protocols which provide a
system-to-system acknowledgement mechanism, expects a one-for-one
acknowledgement for each data unit sent.  The DATA.request primitive
allows the user to pass data to the provider of the data transmission
service (1.  Data sent), and the DATA.confirm primitive is returned
to the user upon receipt of that data's acknowledgement (4.  Ack
returned to user).

      The example in Fig. 2 demonstrates how each data unit is
acknowledged by a separate primitive exchange in a one-for-one data
acknowledgement system.  Some system implementations want to reduce
the number of primitive exchanges in order to improve performance.
This can be accomplished by providing an acknowledgement mechanism
that is not coupled to each data unit that is transmitted.

      This method for efficient, user-driven data acknowledgement
between two local entities greatly reduces the number of primitive
exchanges while maintaining the acknowledgement information.

      Data is sent by the user entity to the provider entity in a
DATA.request primitive.  The DATA.request primitive construct is
divided into two parts: the Interface Control Information which
contains control information such as addressing and length fields,
and the Interface Data part which contains the data.  The format is
shown in Fig. 3.

      A new field, the Indicator Byte, is added to this primitive.
Within the Indicator Byte is the Confirm Solicitation Indicator (CSI)
bit, used by the user to solicit a confirm from the provider once the
data contained in this primitive has been serviced (that is, the data
has been sent).  This allows the user to explicitly request the
provider to send a confirm that carries acknowledgement information.
Since this confirm is sent only w...